1. Field of the Invention
The present invention relates to an electronic picture stabilizer and a video camera utilizing the same. More specifically, the present invention relates to an electronic picture stabilizer which is utilized in a consumer-purpose camcorder, and a video camera utilizing such a picture stabilizer.
2. Description of the Prior Art
In the past, in order to correct an unintentional motion component of an image sensing device, a method utilizing a portion motion vector obtained for each detection area according to a representative point matching method is proposed. As a prior art in which an electronic picture stabilization is performed with utilizing such a portion motion vector, the same assignee of the present invention has proposed one method disclosed in Japanese Patent Application Laying-open No. 7(1995)-38800. In this prior art, a minimum correlation value, a mean correlation value and position data are evaluated by a calculation circuit for each of detection areas, and applied to a microcomputer which evaluates a portion motion vector on the basis of the position data of a pixel indicating the minimum correlation value.
Furthermore, the microcomputer detects on the basis of the mean correlation value and the minimum correlation value whether the portion motion vector of the detection area is due to the unintentional motion or otherwise so as to determine whether the detection area is a valid area or invalid area.
Furthermore, a whole motion vector is detected by the microcomputer according to methods which are different from each other in accordance with the number of the valid areas out of all the detection areas, and the unintentional motion is corrected on the basis of the whole motion vector.
For example, as shown in FIG. 17, by cutting a portion of an image out and moving a cut-out position according to the whole motion vector, the unintentional motion is corrected.
However, in the above described prior art, if a moving object passed through the detection area, not only the valid areas but also invalid areas are detected. In such a case, a whole motion vector is affected by the invalid area, and therefore, there is a possibility that an operation of the picture stabilization or the correction of the unintentional motion is crippled. More specifically, when the moving object enters into a plurality of detection areas as shown in FIG. 18, for example, the detection areas A and C become invalid areas, and therefore, the number of the valid areas is decreased, and accordingly, a reliability of the whole motion vector becomes low, and therefore, there is a possibility that an accuracy of the picture stabilization becomes bad.